Core architecture

- Retained UI tree
- Damage tracking + partial redraw
- Window tree + z-order control
- Focus graph + keyboard routing
- Pointer hit-test + capture model
- Theme and style primitives

Desktop primitives

- Taskbar + start menu model
- Launcher/search integration
- Window chrome controls (min/max/close)
- Icon grid and wallpaper service hooks
- Shell dock/status area integration

Input model

- Keyboard, mouse, and touchpad abstraction
- Left/right click mapping
- Movement smoothing + sensitivity controls
- No axis reversal and no edge-lock behavior
- Deterministic focus transfer rules

Production gates

1) Compositor path must be default boot UI
2) No major flicker under drag/resize/input stress
3) App launcher and taskbar actions stable
4) Full keyboard-only navigation path available
5) 24h GUI soak without corruption or lockups